<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<script type="text/javascript">
     function A(){
        this.abc=12;
     }
     A.prototype.show=function(){
         alert(this.abc);
     }

    
     //继承A
     function B(){
        //this -> new B()
         A.call(this);
     }

     
     B.prototype=A.prototype;


     var obj=new B();
     //alert(obj.abc)

     obj.show();
</script>
</head>
<body>
	
</body>
</html>